Babylonian Captivity (1309-1377)

Seeing the trouble in Rome over the new Pope Urban Philip IV (France) makes Cardinals choose French Pope: Clement V. Clement settles in Avignon to avoid trouble (plus he's sick). Basically a puppet of the French king, the Pope resides in Avignon until 1377 when Martin V moves back to Rome after the Great Schism.

Decentralized papacy and the increased concern of Pope in secular matters decreases church prestige, makes people inclined to switch to Protestantism